(CNN) -- Those battling global warming by promoting biofuels may unintentionally be adding to skyrocketing world food prices, creating what one expert calls "a silent tsunami" in developing nations.

The rising prices are "threatening to plunge more than 100 million people on every continent into hunger," Josette Sheeran, executive director of the United Nations' World Food Program, said on the agency's Web site Tuesday.

Sheeran is one of the experts attending a Food summit hosted Tuesday by British Prime Minister Gordon Brown, aimed at determining ways to boost food supplies and identify deterrents. Also attending the meeting are scientists and representatives from the European Union and Africa.

On the Web site, Sheeran said the increase in food prices is "a silent tsunami that respects no borders."

"The world's misery index is rising ... as soaring food and fuel prices roll through the lives of the most vulnerable," she said Friday.

The crisis is forcing the organization to look for cuts in aid to some of its recipients, she said.

Soaring food prices have triggered violence in some developing countries, and biofuels are bearing at least part of the blame.

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Producing fuel from plant crops is supposed to be greener than drilling for oil, and biofuels generally burn cleaner, too. But the global biofuels industry now stands accused of a list of side effects that are said to be damaging lives, especially of the world's poorest people.

"The drive for more biofuels means more investment is going into those crops, meaning less land and less investment going in for food crops, causing a massive conflict and resulting in rising prices, which is having a huge negative impact, especially on developing countries," said Clare Oxborrow, food campaigner for Friends of the Earth. See why tortilla makers are blaming biofuel for increasing food prices »

Critics also say that in Africa, Asia and South America, people are being driven from their land and forests are being cleared to make room for the booming biofuel industry.

The International Food Policy Research Institute says the use of cereals for industrial purposes like making biofuels has risen by a quarter since 2000.

Brown said in an article posted on the 10 Downing Street Web site, "We now know that biofuels intended to promote energy independence and combat climate change are frequently energy-inefficient.

"We need to look closely at the impact on food prices and the environment of different production methods and to ensure we are more selective in our support. If our UK review shows that we need to change our approach, we will also push for change in EU biofuels targets," he said.

"We must also do more to explore the links between climate change and food, and particularly their impact on the livelihoods and vulnerability of the very poorest, who are likely to be most affected by climate change."

The meeting he convened, Brown said, is a precursor to the G8 summit of industrial nations, to be held in July, and a special U.N. summit in September.

He urged prompt action.

"With one child dying every five seconds from hunger-related causes, the time to act is now," Brown stressed.

The World Health Organization views hunger as the No. 1 threat to public health around the world, responsible for a third of child deaths and 10 percent of all disease.

Douglas Alexander, Britain's International Development secretary, announced Tuesday that Britain has set aside a 455 million-pound [$900 million] aid package to address the food crisis. His agency manages Britain's aid to poor countries with the goal of eliminating extreme poverty.E-mail to a friend